1. Field of the Invention
The present invention relates to a method and an apparatus for manufacturing a molded product having a thin film, and the method and the apparatus form a molded product made of a resin by injection molding, convey the molded product to a film formation chamber, and form a thin film on a predetermined surface of the molded product.
2. Description of the Related Art
Examples of a molded product, which has a thin film having a thickness of the order of 0.1 to several μm on a part of the surface thereof, include a front lamp provided on an automobile, a CD/DVD on which digital data are recorded, a transparent electrode of a liquid crystal display, and a toy having a metallic luster. These molded products having thin films are formed as follows: a molded product, which becomes a base material, is injection-molded by an injection molding machine; the molded product is carried into a film forming device as a workpiece, on which a film is to be formed; and a film is formed on the molded product. Not only the injection molding machine but also the film forming device has also been known. There are various kinds of injection molding machines, such as an injection molding machine including a toggle type mold clamping device and an injection molding machine including a direct pressure type mold clamping device, but the injection molding machine basically includes a pair of molds, a mold clamping device, an injection device, and the like. Accordingly, the pair of molds are clamped by the mold clamping device, and a resin as a material is melted in the injection device, and a molten resin is injected into cavities formed in the molds. After the molten resin is solidified by cooling, the mold clamping device is driven so that the pair of molds are opened. Accordingly, molded products are obtained.
The film forming device includes a film formation chamber. Incidentally, various kinds of film forming devices are provided according to a film forming method. For example, a sputtering method, an ion-plating method, a plasma film forming method and the like are known as film forming methods. The sputtering method is of forming a thin film by disposing a target material so that the target material faces the surface of a workpiece, on which a film is to be formed, applying a negative voltage in the range of several hundred V to several kV to the target material in an argon gas atmosphere with a pressure of about several to several tens of Pa, and discharging electricity; an electron beam deposition method of forming a film on the surface of a workpiece, on which a film is to be formed, by irradiating a target material with an electron beam, which is generated from an electron gun, in a vacuum chamber so as to evaporate the target material through heating. The ion-plating method is of performing vacuum deposition on a workpiece, on which a film is to be formed, under the pressure of an argon gas of several Pa by applying a negative voltage in the range of several hundred V to several kV to the workpiece. Further, a chemical vapor deposition method is also known as a film forming method. Compound targets, such as an oxide, a nitride, and a carbide, are known as the target material used in these film forming methods, and a metal target, a powder target, and the like are also known as the target material. There are various kinds of film forming methods as described above, and film forming devices suitable for the respective film forming methods are provided.
Incidentally, if dirt from the hands or dust adheres to the molded product when a film is formed on a molded product, it is not possible to appropriately form a film and unevenness also occurs on a thin film to be formed on the molded product. Accordingly, when the molded product, which has been formed by injection molding, is conveyed to the film forming device, it is necessary to prevent dirt from the hands or dust from adhering to the molded product. Further, immediately after the molded product is formed, the temperature of the molded product is high. However, when heat is reduced after the molded product is left, moisture is adsorbed in the molded product. If moisture is adsorbed in the molded product, hindrance occurs when air is sucked from the film formation chamber and the quality of a thin film to be formed deteriorates. For this reason, it is necessary to evaporate moisture adsorbed in the molded product by heating the molded product in advance when forming a film.
Japanese Patent No. 3677033 discloses an apparatus for manufacturing a molded product having a thin film that covers the inner surface of one semi-hollow body of a pair of semi-hollow bodies molded by a stationary mold and a movable mold, that is, the surface of a molded product with a film forming chamber that is provided with deposition elements, such as a target electrode, a substrate electrode, and a vacuum suction pipe, and performs deposition, that is, the formation of a film in the stationary mold while the semi-hollow bodies remain on the stationary mold. JP-A-2011-58048 discloses an apparatus for manufacturing a molded product having a thin film that includes an injection molding machine conveying a molded product formed by the injection molding machine to a film forming device while keeping the molded product warm by a heater, a film forming device, and a conveying device.